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UNITED STATES PATENT OFFICE.

FOLDING SQUARE.

Specification of Letters Patent.

Patented Nov. 28, 1905.

Application filed October 24, 1904. Serial No. 229,747-

To all whom it may concern.-

Be it known that I, THOMAS J ARVIS, a citizen of the United States. residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Folding Squares, of which the following is a specification.

This invention relates more particularly to folding squares for carpenters use, but is also applicable to tailors squares, drafting-squares, hook log rules, and the like.

It consists in the combination of two members adapted'to form a suitable square with a hinge or joint which will allow said members to be folded together or to be swung apart to any desired angle, preferably a right angle, and securely locked in said open position; and it further consists in the combination, with the folding members, of a cap or cover adapted to inclose the joint and also to hold the members in closed or parallel position.

A further element or feature consists of a device for freeing the locking-spring, as will be described hereinafter.

The objects of this invention are to provide a folding square or device of the character set forth which will have substantially no projecting parts at the joint end either when folded or open, which will have a rigid and substantial joint or hinge and locking means for holding the members in open position, and in such other desirable features as will be described in the specification.

This invention is shown in the accompanying drawings, in which Figure 1 is a side view showing the parts of the square in folded position with the end cap in place. Fig. 2 is an enlarged plan view showing the square with the parts in position for use, a portion of one of the arms being broken away to disclose the locking device. Fig. 8 is an edge view of the square as shown in Fig. 2. Fig. A is a detail showing one of the arms of the square provided with a curved engaging tongue or flange.

As shown in the drawings, 5 represents one of the arms or members of the square, which in a carpenters square is usually somewhat longer than the other arm or member 6. The arm 5 is slotted at one end, as shown at 7, and also beveled for a portion of its width, as shown at 8, said beveled portion terminating in a shoulder 9. The arm or member 6 is provided at its hinged end with a curved tongue or flange 10, which takes into the slot 7 of the arm 5. This curved tongue is provided with a shoulder 11 at right angles to the arm 6 and at the end of the arm is provided with a beveled notch 12. This notch is adapted to engage with a correspondinglybeveled shoulder 13 on a locking-spring 14, which is secured in the slot 7 along the outer edge of the arm 5. This spring is preferably held by means of two rivets 15, but may of course be secured in any other desired manner. The end of the arm 6 is beveled at 16 to correspond with and also to engage with the beveled end 8 of the arm 5. The bevel 16 also terminates in a shoulder 17 which is adapted to engage with the shoulder 9 of the arm 5, as will be clearly seen in Fig. 2. The joint or hinge is completed by means of a pivot 18, which passes through the sides of the arm 5 at its slotted end and engages with a hole 19 in the flange or tongue 10, the pivot or rivet being located so that the arms will fold closely together when in closed position and so that when the beveled and shouldered portions come together in the open position the arms will be at right angles and the spring 14 will be in engagement with the shoulder 12 of the flange 10. The particularly-beveled character of the engaging shoulder of the spring and of the flange is an important feature, inasmuch as it will insure an absolutely tight holding of the arms when in open position, the spring tending to crowd down onto the beveled shoulder of the flange.

When the square is to be folded, a pin or pry, as indicated in dotted lines 20 in Fig. 2, is introduced between the end of the spring and the flange to pry the spring out of en gagement with said flange. This is desirable, as the spring should be sufficiently strong to prevent any movement of the arms of the square. 7 An ordinary nail will usually be found convenient for pressing back the spring. When the arms are folded, as shown in Fig. 1, it is desirable to provide means for holding them in said folded position and also means for covering the joint to prevent dirt from gathering in the same. I have accomplished both of these objects by means of a cap 21, which slips over the end and holds the parts in closed position. A screw, such as shown at 22, may be used as an alternative means of holding the arms in open position in place of the spring 14:.

Having thus described my invention, which I do not wish to limit to the exact details of construction herein shown and described, what I claim, and desire to secure by Letters Patent, is

1. In a folding square or the like,the combination of two arms pivotally connected at one end, a beveled shoulder on one of said arms, and a spring provided with a beveled shoulder on the other of said arms, said spring being adapted to engage with the beveled shoulder on the arm to hold the arms rigidly in open position and to take up lost motion between the parts.

2. In a folding square, the combination of an arm provided with a slotted end, a second 

